Masters Theses
Substrate use during and following high and low intensity exercise : implications for weight control
Date of Award
5-1997
Degree Type
Thesis
Degree Name
Master of Science
Major
Human Performance and Sport
Major Professor
Dixie L. Thompson
Committee Members
David R. Bassett, Edward Howley
Abstract
Fat metabolism and total caloric expenditure during exercise have been the major foci for researchers investigating the impact of physical activity on weight loss; however, there is little research exploring the utilization of fat in the post-exercise period. The purpose of this study was to examine substrate utilization during and after two exercise bouts of different intensities, but with similar caloric expenditures, in an attempt to determine which exercise intensity was associated with a greater reliance on fat.
Ten male subjects participated in this study. All subjects had been physically active 6 months prior to the study and engaged in activity at least 3 days a week for a minimal of 30 minutes a session. Subject's average age, height, and weight were as follows: 26.9 (±4.8) years, 181.1 (±4.8) cm, and 75.7 (±8.8) kg. An incremental cycle ergometer test was performed by each subject to determine their maximal oxygen consumption (VO2 max). On subsequent days, subjects performed cycle ergometer exercise at 33% VO2 max for 90 minutes and 66% VO2 max for 45 minutes. Throughout the 6 hour recovery period, oxygen consumption was continuously monitored by the SensorMedics 2900 Metabolic Cart. Subjects were fed a standard meal 2 hours post-exercise.
During exercise, carbohydrate utilization was signifcantly (p < 0.05) greater during the high-intensity trial compared to the low-intensity trial (106.0 ± 27.8 g vs. 68.7 ± 20.0 g, respectively). Fat and protein utilization were greater during the low-intensity bout compared to the high-intensity bout (30.0 ± 11.0 g and 4.9 ± 2.9 g vs. 13.6 ± 6.6 g and 1.6 ± 0.6 g, respectively). Caloric expenditure between exercise bouts were similar.
Oxygen consumption throughout the 6 hour post-exercise period was not different between exercise bouts; however, average pre-meal VO₂ was significantly higher following the high-intensity exercise compared to the low-intensity exercise (288 91.3 ml/min vs. 264 ± 48.6 ml/min, respectively). The R value was not different between exercise trials throughout the entire recovery period or during pre- and post-meal recovery periods. EPOC duration was similar between exercise bouts (60 minutes). After meal consumption, VO2 never returned to baseline values in either exercise trial.
Total caloric expenditure (exercise and recovery combined) was not significantly different between exercise trials; however, total carbohydrate utilization was significantly greater during and after the high-intensity bout (188.8 ± 45.2g) compared to the low-intensity bout (142.5 ± 28.5 g). Total fat utilization was significantly greater in the low-intensity bout compared to the high-intensity bout (42.4±13.6 g vs. 24.0 12.2 g, respectively). Total protein utilization was similar for the low- and high-intensity trials.
Substrate utilization was similar between exercise bouts throughout recovery, therefore, the significant difference in total substrate utilization is due to the exercise bout itself. These results imply that low-intensity exercise is more beneficial for fat utilization than high-intensity exercise at the same caloric expenditure.
Recommended Citation
Townsend, Karen Michelle, "Substrate use during and following high and low intensity exercise : implications for weight control. " Master's Thesis, University of Tennessee, 1997.
https://trace.tennessee.edu/utk_gradthes/10738